1. Field of the Invention
The present invention relates to a method of attaching a small sewing part to a main sewing part to form a pocket insert, and to a device by which said method is carried out.
2. Description of Related Art
One prior method in this field was described in the journal "DNZ", No. 9/1987, on page 44, which includes a picture captioned "Production of a Breast Selvage Pocket". In this known method for the production of a breast selvage pocket, a main sewing part, with its front side facing upward, is spread out on the worktable of the automatic sewing machine and aligned in accordance with the proper seating of the pocket insert which is to be made. Then the main sewing part is held fast in fixed position on the worktable by a lowered clamp for the material being sewn. Finally, a prefabricated small sewing part is placed by hand, with its visible side downward, at a predetermined place on the sewing-material clamp. After the small part has been clamped fast on the sewing-material clamp, the latter transports the main part and the small part to the sewing station and then to the cutting station.
For aligning the small part and the main part for proper pattern-matching, it was heretofore customary in the industry for the exact position of the small part to be designated by corresponding markings on the main part, for guiding the subsequent sewing of the small part onto the main part. These markings corresponded to the corner points of the small part, and fixed the course of the seam to be sewn. In order to optimally utilize the capacity of an automatic pocket insert sewing machine, these markings were made by another employee at an additional workplace located as close nearby as possible. But in he case of prefabricated sewing parts of patterned material, mismatches in pattern between the small part and the main part sometimes were discovered after the small part was sewn on, and as a result, disagreeable disputes, prejudicial to the working climate, frequently arose as to which workplace--the workplace for the marking step or the workplace for the locating and aligning steps--had made the mistake.
As a matter of fact, incorrect marks, incorrect alignment of the marked main part (which may be placed on the worktable under the guidance of marking lights), and incorrect application of the small part, are all possible causes for the small part being sewn on without proper matching of the pattern.
In order to avoid these problems, another method of operation, described briefly below, has at times been used. In accordance with this method, the small sewing part is aligned with its pattern matched to the main part directly on the automatic sewing machine, and then, both the main part and the aligned small part resting on it are shifted in such a manner--without interfering with the alignment--hat the end points of the small part coincide with light markings produced by marking lights. (In this case, the aforementioned marking step can be dispensed with)
Both the one method (with marks) and the other method (without marks) have the following problem: The front side of the small sewing part must face upward in order to match its pattern to the main sewing part. But then the small part, starting from this position, must be turned through an angle of about 180.degree. before being placed at the predetermined spot on the sewing-material clamp, since the first step in attaching the small part to the main part is to sew its still-open longest side to the main part with the visible side of the small part facing downward
Thus, the two operations which have just been described have the common disadvantage that the operator, after the above-described pattern-matching alignment, must manually remove the small part from the main part, which, in the meantime, has been fixed in position, and then place it with its front side facing downward on the sewing material clamp, which is present in the meantime at the feed station, as shown in the above-cited prior art publication.
In addition, the position-limiting stops on the sewing material clamp must be adjusted very carefully, to achieve the desired sewing and pattern-matching results. Both methods of operation have the disadvantage that when the small part is removed and placed on the sewing material clamp, the small part can pull or stretch, particularly if it is made of loosely woven goods. This pulling or stretching makes it impossible for the pattern of the small part to match the main part after it is sewn on, even though the small part has previously been aligned on the main part with its pattern precisely matched.